Each year approximately 900,000 Americans suffer a myocardial infarction. Approximately 225,000 of these victims die and the others are at risk for chronic complications, including congestive heart failure and intractable ventricular arrhythmias. Unlike other organs such as the liver, the heart is unable to regenerate and replace the lost myocardial cells to any significant extent. Much effort is now being expended to find ways to induce, stimulate, and augment myocardial regeneration. One promising approach is transplantation of undifferentiated stem cells into the infracted zone. One bottleneck in stem cell transplantation is the acquisition of a sufficient number of stem cells to be infused into the patient. There is much interest in using donor cells that are derivatives of embryonic stem cells (ES cells). Because of ethical concerns about destroying human embryos, much attention has been focused on obtaining ES cells by other means. One potential solution is to reprogram a patient's own somatic cells so that they become more like stem cells. Nuclear reprogramming the process by which the nucleus of terminally differentiated cells becomes more like the nucleus of an undifferentiated stem cell. The goal of the experiments in this proposal is to reprogram differentiated cells with extracts of Xenopus eggs. Our approach will be to expose permeabilized cells to concentrated egg extracts then assay the extent of reprogramming by transplanting them into enucleated Xenopus eggs. Reprogramming will be indicated by improved development of eggs that receive extract-treated nuclei compared to those that receive untreated nuclei. If we can demonstrate reprogramming by extracts, then we can investigate various reprogramming models by treating the extract with inhibitors or eliminating specific proteins by immunodepletion. It may even be possible to purify protein complexes with reprogramming activity. The results of our studies will shed light on the nature of the epigenetic changes that drive cell differentiation. We also hope to develop extracts that efficiently reprogram differentiated cells so that they can be used for cell replacement therapy. PUBLIC HEALTH RELEVANCE: Heart attack survivors are at risk for developing heart failure because the heart cannot repair and regenerate itself like some other organs. In recent years, heart attack victims have been treated with stem cells in the hope that these will be able to turn into heart muscle cells and restore the heart's pumping function. The purpose of this proposal is to treat normal cells with extracts of egg cells to see if they can be turned into stem cells in the hope that these can be used to repair the heart.